Garlic Mustard

Alliaria petiolata

Background

Garlic mustard is an invasive herb native to Europe. It was brought to North America in the early 1800s for use as an edible herb. Available in the early spring and high in vitamins A and C, it has a strong, distinctive smell similar to garlic. Since its arrival in North America it has escaped into the wild and is now one of Ontario’s most aggressive forest invaders.

Garlic mustard has two distinct life stages over its first two years. In the first year, it grows only a cluster of leaves shaped like a rosette, while a strong root system develops. Plants that survive the winter produce flowers and hundreds of seeds in their second year. Dense stands produce more than 60,000 seeds per square metre. Stands of garlic mustard can double in size every four years.

Garlic mustard seeds are easily spread by people and animals. They can remain in the soil for up to 30 years and still be able to sprout. The plant can grow in a wide range of sunny and fully shaded habitats, including undisturbed forest, forest edges, riverbanks and roadsides. Garlic mustard does not provide a valuable food source for native wildlife.

Range

Garlic mustard is established in southern and eastern Ontario as far north as Sault Ste. Marie, in parts of Quebec, and south to North Carolina and Kentucky in the United States. Isolated populations have been found in British Columbia, Nova Scotia, Prince Edward Island and New Brunswick.

Impacts of Garlic Mustard

Garlic mustard can invade relatively undisturbed forests. Once established, it can displace native wildflowers like trilliums (Trillium sp) and trout lily (Erythronium americanum). It hinders other plants by interfering with the growth of fungi that bring nutrients to the roots of the plants.

Lower leaves are broad, kidney-shaped and up to 10 centimetres across. Upper leaves are triangular and five to 10 centimetres across, narrowing towards the tip.

Second-year plants produce white flowers with four small petals in May.

Narrow seed pods 2.5 to six centimetres long split open in mid-summer to reveal tiny black seeds.

Garlic mustard resembles several native Ontario plants. The leaves at the base of the plant look like those of several plants in the carrot family (Thaspium and Zizia), the daisy family (Senecio) and the violet family (Viola). The seed pods look like those of several other mustard (Brassicaceae) species. The easiest way to distinguish garlic mustard from these plant families is to crush the leaves. If they emit a strong garlic smell, then the plant is most likely garlic mustard.

This website is operated by the Ontario Federation of Anglers and Hunters (OFAH) as Administrators of the Invading Species Awareness Program (ISAP) and the opinions expressed or implied herein do not necessarily represent those of the Ministry of Natural Resources and Forestry (MNRF).